I'm not trying to take anything away from the Raven, and I find them important in most TvT and some TvZ. But in my opinion they're really expensive considering other unit(s) you can get. I also find the seeker missiles very, very, very situational. It was good in the beta before the nerf. The main problem is that their deployment range is 0, and their tactical range is 6 (upgradeable to 7) That means that unless an opponent is willing to charge right into your temporary fortifications, the Raven has to get unreasonably close to enemy fire, and even then, the enemy can simply retreat a short distance and fight somewhere the weapons aren't. There are no situations other than when the opponent having a ton of air units stacked together that SM justifies the 125 energy and 150/150 minerals it costs to have it researched, in my opinion anyway.

The thing with the Infestor, I find the overall cost of the unit along with the useablity of its spells against all 3 races the main reasons why I consider it the best caster in the game (in my opinion). Neural Parasite, even though I don't always bother to research it unless I see Thors or Collossi on the field (and even though it's been nerfed) still has uses. And I can't say enough about Fungal Growth, I love it, looooove it. The fact that the Infestor also moves while burrowed, and can cast Infested Terran while burrowed, I'm still really surprised they made that change, I thought that was a bug during the beta . I feel strongly that the Infestor is such an unappreciated unit, I highly recommend checking out the TheLittleOne games especially when he plays as Zerg, he always utilizes Infestors.